1. Field of the Invention
The present invention relates to a polymeric reagents capable of reacting with the carbonyl functional group of a carbonyl compound, thereby enabling the isolation of the carbonyl compound or the protection of the carbonyl functional group from later reactions. More particularly, the invention relates to a polymeric material having functional groups of the formula --ONH.sub.2 capable of such reaction.
2. Description of the Prior Art
Various reagents are available for the isolation of trace amounts of carbonyl compounds from complex mixtures containing many different impurities. The separation is generally accomplished by separating components into various phases. Since high molecular weight carbonyl compounds and most other organic compounds with which they are normally contaminated are normally soluble in organic solvents and insoluble in water, the most common separation techniques now used involve the conversion of the carbonyl compound into a water soluble form, separation of the aqueous from the non-aqueous phase, and reconversion of the carbonyl compound into its original form. The most commonly used reagents for accomplishing this are Girard reagents such as Girard reagent T (trimethylaminoacetohydrazide chloride).
However, these reagents are not suitable for all carbonyl compounds. For example, difficulty has occurred in attempting to isolate steroid hydroxy ketones esterified with various long chain fatty acids. Such compounds are known as lipoidal derivatives of steroids. The isolation of such molecules presents a special problem in that they are highly liphophilic, and tissue extracts containing these compounds are always contaminated with large amounts of triglycerides and other non-polar compounds. These lipoidal derivatives of steroids are so liphophilic that the partitioning of their Girard hydrazones between an aqueous and an organic phase is uncertain. In addition, the solublizing effect of the contaminating lipids helps reduce the water solubility of the hydrazones upon which this isolation technique depends. Furthermore, such liquid-phase separation techniques require manipulating large volumes of solvent when only trace amounts of a ketone is present in an extract containing very much larger quantities of non-ketonic lipids.
Accordingly, various prior art references have suggested the use of polymer-bound reagents in order to effect a solid-liquid phase separation. Polymer-bound 1,2-diols and 1,3-diols have been synthesized for the separation and protection of carbonyl functional groups. While these reagents have been found to form acetals with aldehydes in good to excellent yields, they have been less successful in their reactions with ketones.
Several reagents have been proposed which resemble a Girard reagent attached to a solid phase. For example, the preparation of a polymeric acrylate hydrazide and its use as an absorbant for carbonyl compounds was described in Namiki et al., Nappon Nogei Kagaku Kaishi, 35, 570 (1961). This reagent was prepared by forming a polymer from methyl acrylate crosslinked with divinylbenzene. Some of the pendant carboxylic acid ester groups were converted into hydrazide functional groups as shown in the following reactions scheme: ##STR1## This reagent was shown to be able to remove carbonyl compounds from solution, but the recovery of the bound compounds from the resin was not reported. Recent work by the present inventors has indicated, however, that recovery of bound compounds from hydrazide-containing, solid-phase reagents is incomplete and that the Namiki resin does not bind steroidal ketones. Accordingly, a new polymeric reagent is needed which will react efficiently with liphophilic and other ketones and which will release bound ketones and aldehydes from the polymeric carrier under mild conditions.